Make a PDF smaller in four steps
- Drop one or more PDFs onto the tool above, or click it to choose them.
- Under Compression, choose Light, Balanced (the default) or Strong.
- Click Compress PDF. A progress line counts through the images in each file.
- Check the before and after sizes shown for each file, then download it, or use Download all (ZIP) for several.
Not happy with the result? Pick another level and compress again. Every run starts from your original file, so quality losses don’t pile up, and the original on your disk is never changed.
How this PDF compressor works
A PDF stores different kinds of content in different ways. Text is kept as characters plus the fonts needed to draw them, charts and logos are often vector drawing instructions, and photos and scanned pages are embedded as images, usually JPEG. The text and vector parts are compact. The images are almost always what makes a PDF large.
So pd00 goes after the images. It finds each standard JPEG photo inside the file, scales it down if it is larger than the preset allows, and re-encodes it at a lower JPEG quality. A re-encoded photo replaces the original only when it comes out noticeably smaller. Text, fonts and vector graphics are not touched, so text stays sharp at any zoom and remains selectable and searchable, and pages stay in the same order. Finally the file is saved again with its internal structure packed more tightly.
One rule always holds: pd00 never hands back a file larger than the one you gave it. If the re-saved file wouldn’t be smaller, you simply get your original back, and the result line says the file is already compact.
All of this happens inside your browser tab. The PDF is never uploaded: the page’s Content-Security-Policy only allows connections to pd00.com and Cloudflare’s anonymous page-view counter, and neither ever receives your document. You can check this in DevTools by following the steps on our privacy page.
Light, Balanced and Strong compared
| Preset | Photos limited to (long edge) | JPEG quality | Good for |
|---|---|---|---|
| Light | 2,400 px | 80 | Documents you may print; a modest saving with little visible change |
| Balanced (default) | 1,700 px | 68 | Email, upload forms and reading on screen |
| Strong | 1,200 px | 55 | Squeezing under a strict size limit |
To picture those sizes, think of a photo that fills a letter-size page, 11 inches on its long side. At 2,400 px it has about 218 pixels per inch, at 1,700 px about 155, and at 1,200 px about 109. Around 150 is comfortable for reading on screen and printing ordinary documents; fine photographic prints need more. A photo that only fills part of the page keeps proportionally more detail. Photos already smaller than the limit are not enlarged; they are only re-encoded.
The quality numbers use the browser’s 0–100 JPEG scale, which doesn’t line up exactly with the scales other apps use. At 55, fine textures and small print in scans can look slightly soft or blocky.
Which PDFs shrink a lot, and which barely change
- Big savings: scans saved by a copier or phone scanning app as JPEG pages, PDFs built from phone photos, and photo-heavy brochures, listings and reports.
- Little or no saving: text-only documents exported from a word processor, because they contain nothing to recompress; PDFs that were already optimized; and files whose images aren’t standard JPEG.
That last group needs a word of explanation. Only standard JPEG photos are recompressed; other image types inside a PDF are left as they are. Black-and-white scans, for example, are often stored in special fax-style formats rather than JPEG, so they may not change much. When a file does shrink, the result line also shows how many of its JPEG photos were recompressed.
Getting under an email attachment limit
Email services commonly cap attachments at around 20–25 MB, and some count the encoded size, which runs about a third larger than the file on disk. If you are near the limit, leave headroom. Upload forms for job applications, schools and government services often have tighter caps of their own.
If Balanced isn’t enough:
- Try Strong. It is the biggest reduction available here.
- Send fewer pages. Use Split PDF to divide the document into two emails, or extract just the pages the recipient asked for.
- Rebuild from the source photos. If the PDF was made from photos you still have, convert them again with JPG to PDF and choose a smaller max size, such as 1280 px.
There is no “compress to exactly 1 MB” setting. You pick a level and see what comes out, which is why the before and after sizes are shown next to each file.
Trade-offs and times to leave a PDF alone
- Some photo detail is lost. That is how the file gets smaller. Keep the original if you might need to print photos at high quality later.
- Official originals. If a lender, agency or court asks for the original file, send the original, not a compressed copy.
- Password-protected PDFs can’t be opened. Remove the password in your usual PDF app first.
- No other edits. The tool doesn’t remove pages, run OCR or convert to Word. To drop pages, use Split PDF.
- Very large files on phones. The whole PDF is held in memory, so files of several hundred megabytes are better compressed on a computer.